Genetic characteristics of streptomycin-resistant streptococci.
Explore the source record for details and available documents.
DNA, Bacterial↗
Biomedical subjects
D Perry
Publications and source records attributed to D Perry.
Accumulation of 14C-streptomycin by streptomycin-sensitive and streptomycin-resistant group H streptococci.
Three streptomycin-resistant mutants of group H streptococcus, strain Challis, were examined for ability to accumulate (14)C-streptomycin. Although the mutants exhibited different levels of transformation, only the streptomycin-sensitive parent Challis strain accumulated significant amounts of (14)C-streptomycin. It appears that impermeability to streptomycin does not necessarily result in reduction or loss of transformability. The amount of label accumulated by strain Challis was correlated with a loss of viability. In addition, accumulation of label was influenced by the concentration of (14)C-streptomycin, the time of exposure, and the type of medium employed.
Carbon Isotopes↗
Transformability of streptomycin-resistant group H streptococci.
Several resistant mutants of a transformable group H streptococcus, strain Challis, were isolated from media containing high concentrations of streptomycin. Mutants SR5a and SR5 exhibited high and low transformability, respectively, when exposed to deoxyribonucleic acid (DNA) from a novobiocin-resistant Challis strain. With similar exposure, mutant SR30 exhibited loss of transformability. The mutants further differed from the parent strain in time of appearance of optimal competence, and, in the case of SR5 and SR30, total growth was somewhat less than that of the parent. The rapidity with which transformants appeared upon initial exposure to DNA was approximately the same in the mutants and the parent strain. The decrease or loss of transformability of mutants SR5 and SR30 was found to be due to an alteration in capacity to take up DNA. Mutant SR5a (highly transformable) was further differentiated from mutants SR5 and SR30 in that it was somewhat more sensitive to high concentrations of streptomycin. Transformants obtained by treating strain Challis with the three types of mutant DNA, on the other hand, exhibited similar degrees of resistance to increasing concentrations of streptomycin. The additional decrease in transforming ability of mutant SR5a and the loss of transforming ability of mutant SR5 after a second exposure to streptomycin may indicate a stepwise process in the change from transformability to nontransformability. Although streptomycin resistance may not be directly related to inability to transform, results indicate that streptomycin greatly increases the chances of selecting these mutants and also can be of value in serving as a marker in studies of this nature.
DNA, Bacterial↗
Fetal incubator studies. II. Fetal alveolar electrolyte excretion.
Explore the source record for details and available documents.
Animals↗
Effect of filtrates from transformable and nontransformable streptococci on the transformation of streptococci.
Perry, Dennis (Northwestern University Medical School, Chicago, Ill.), and Hutton D. Slade. Effects of filtrates from transformable and nontransformable streptococci on the transformation of streptococci. J. Bacteriol. 91:2216-2222. 1966.-The nature of the transformation competence factor from a group H streptococcus was investigated. The activity of competence factor reached a maximum at the time that optimal competence was attained, the maxima of both occurring in the early log phase of growth. The decrease in competence factor was much more gradual than the decrease in number of competent cells. No inhibitor, however, was detected as being responsible for the decrease in either competent cells or competence factor activity. Efforts to induce transformation in other serological groups of streptococci with the use of group H competence factor were unsuccessful. The development of competence in group H when grown in the presence of nontransformable group A strains resulted in a significant increase in the number of transformants. Culture filtrates from early log phase group A cells also caused an increase in the number of transformants from the group H strain. The addition of 10(-4)m ethylenediaminetetraacetic acid to group A (or group H) culture filtrates caused significant increases in the number of transformants. These results thus indicate that group A streptococci, although nontransformable, produce low levels of "competence factor." Late culture filtrates from the group H streptococcus and several strains of group A streptococci possessed deoxyribonuclease-like activity which inhibited the transformation of the group H strain. This activity in the A filtrates, however, was not prevented by group A anti-deoxyribonuclease sera. Instead, these sera also inhibited transformation. Evidence indicates that the lack of transformation of group A streptococci is due to factors other than the production of deoxyribonuclease.
Animals↗
Neuronal protein NP185 is developmentally regulated, initially expressed during synaptogenesis, and localized in synaptic terminals.
Evidence is presented here that demonstrates the presence of NP185 (AP3) in neuronal cells, specifically within syn-aptic terminals of the central nervous system and in the peripheral nervous system, particularly in the neuro-muscular junction of adult chicken muscle. Biochemical results obtained in our laboratories indicate that NP185 is associated with brain synaptic vesicles, with clathrin-coated vesicles, and with the synaptosomal plasma membrane. Also, NP185 binds to tubulin and clathrin light chains and the binding is regulated by phosphorylation (Su et al., 1991). Based on these properties and the data reported here, we advance the postulate that NP185 fulfills multiple functions in synaptic terminals. One function is that of a plasma membrane docking or channel protein, another of a signaling molecule for brain vesicles to reach the synaptic terminal region, and a third is that of a recycling molecule by binding to protein components on the lipid bilayer of the synaptic plasma membrane during the process of endocytosis. In support of these premises, a thorough study of NP185 using the developing chick brain, adult mouse brain, and chicken straited muscle was begun by temporally and spatially mapping the expression and localization of NP185 in evolving and mature nerve endings. To achieve these objectives, monoclonal antibodies to NP185 were used for immunocytochemistry in tissue sections of chicken and mouse cerebella. The distribution of NP185 was compared with those of other cytoskeletal and cytoplasmic proteins of axons and synapses, namely synaptophysin, vimentin, neurofilament NF68, and the intermediate filaments of glial cells (GFAP). The data indicate that expression of NP185 temporally coincides with synaptogenesis, and that the distribution of this protein is specific for synaptic terminal buttons of the CNS and the PNS.
Adaptor Protein Complex 3↗
The effect of stress on salivary cortisol in panic disorder patients.
BACKGROUND: Various findings suggest the possibility of an abnormal cortisol response to CRH in panic disorder patients, which raises the question of whether such patients might also produce an abnormal cortisol response to stress. The purpose of the present study was to use salivary cortisol measurement in assessing differences in response to novelty/mild stress situations between panic disorder subjects and controls. METHODS: Subjects were recruited by means of posters and subsequently screened for suitability as controls or panic subjects. Twenty-four panic disorder (PD) sufferers and 15 panic-free control subjects were tested on a range of psychometric and physiological measures, at both the start and the end of the experiment. Subjects were tested at the beginning for state anxiety, salivary cortisol, heart rate, and blood pressure, and these tests were repeated at the end of the session (which had been designed to promote reassurance). RESULTS: The state anxiety scores (STAI) showed a reduction in anxiety level over the test period, and there was a corresponding fall in both blood pressure and heart rate for both groups. Cortisol levels also fell over the course of the interview in the control group, but in the PD group cortisol levels showed no such reduction. In addition, there was a significant difference in the levels of cortisol at the start of the session between the two groups (PD group lower). CONCLUSIONS: These data indicate a possible alteration in cortisol responsiveness to stress/novelty situations in PD subjects. This was considered to be consistent with previous suggestions of HPA axis dysregulation in PD patients, although our research indicates unresponsiveness rather than responsiveness to be a factor to be considered for future investigation. CLINICAL IMPLICATIONS: Our results suggest that not all subjects suffering PD may benefit from stress reduction therapies as a first choice of treatment for their panic attacks. The existence of nocturnal panic attacks (considering sleep as a combination of mental and physical relaxation), in the absence of nightmares, as well as the induction of panic attacks during relaxation support this view. LIMITATIONS OF THE STUDY: Apart from the difficulty in accessing sufficient symptomatic subjects, the induction of higher levels of stress could be useful for confirmation of these results. However, this requires specialist support in case of subjects developing panic attacks during the experiments, which was not available during the present study. SUMMARY: Twenty-four panic disorder (PD) sufferers and 15 panic-free control subjects were tested on a range of psychometric and physiological measures, at both the start and the end of an experimental session. Subjects were tested at the beginning for state anxiety, salivary cortisol, heart rate, and blood pressure, and these tests were repeated at the end of the session. The state anxiety scores (STAI) showed a reduction in anxiety level over the test period for both groups, and there was a corresponding fall in both blood pressure and heart rate. Cortisol levels also fell over the course of the session in the control group, but in the PD group cortisol levels showed no such reduction. In addition, there was a significant difference in the levels of cortisol at the start of the session between the two groups (PD group lower). These data indicate a possible alteration in cortisol responsiveness to stress/novelty situations in PD subjects. This was considered to be consistent with previous suggestions of HPA axis dysregulation in PD patients, although our research indicates unresponsiveness rather than responsiveness to be a factor to be considered for future investigation.
Adult↗
Isolation, sequence determination and expression in Escherichia coli of the isopenicillin N synthetase gene from Cephalosporium acremonium.
The enzyme isopenicillin N synthetase (IPS) catalyses the oxidative condensation of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (LLD-ACV) to isopenicillin N, which is a central reaction in the pathway to clinically important penicillins and cephalosporins. Here we report the cloning, characterization and expression in Escherichia coli of the gene encoding the IPS protein in Cephalosporium acremonium. The IPS gene was identified by purifying IPS protein, determining the first 23 amino-terminal amino acids, preparing a set of synthetic oligonucleotides encoding a portion of the determined amino-acid sequence, and probing a cosmid genome library with the mixed oligonucleotides. A cosmid hybridizing with the probe was isolated and the IPS gene was localized and sequenced. The IPS gene encodes a polypeptide of relative molecular mass (Mr) 38,416. When this open reading frame was cloned into an E. coli expression vector and inserted into E. coli, the recombinant E. coli produced a new protein co-migrating with authentic IPS as the major protein of the cell (approximately 20% of cell protein). Crude cell extracts condensed LLD-ACV to a penicillinase-sensitive molecule whose antibacterial activity indicated that it was isopenicillin N.
Acremonium↗
Peritonitis due to Stenotrophomonas maltophilia in patients undergoing chronic peritoneal dialysis.
The occurrence of cases of Stenotrophomonas maltophilia peritonitis in chronic peritoneal dialysis (PD) patients prompted a review of our experience with this condition. A search of microbiology records revealed seven episodes of S. maltophilia peritonitis in 7 patients in 1996 - 3.8% of all PD patients - compared to no cases in 1994 and 1995 (p = 0.01). Patients ranged in age from 16 to 64 years; there were 3 males and 4 females. Six of seven episodes of peritonitis were community acquired and one was hospital acquired. No temporal clustering of cases was seen. Patients were from different urban and rural communities. Patients used the same commercially supplied dialysate fluid, different dialysis techniques, and were taught a no-touch technique for connection. Treatment of peritonitis required removal of the Tenckhoff catheter in 4 of 7 cases. Fingerprinting of six available isolates by polymerase chain reaction using primers derived from the conserved region of the 16/23Sr RNA gene sequence and pulsed field gel electrophoresis revealed all to be unique strains. A case-control study comparing 7 S. maltophilia cases to 21 PD controls showed case patients to be younger and more likely to be on immunosuppressive therapy. We conclude that S. maltophilia has emerged as an important cause of peritonitis in our continuous ambulatory PD population. Evidence to date suggests community acquisition with no evidence of a common source.
Adolescent↗